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in South Taylor, the Division was required to calculate potential productivity <br />declines on irrigated areas in order to approve the South Taylor mining. This <br />analysis was necessary to allow mining where there could be impacts to <br />irrigated lands, pasture lands and/or alluvial valley floor areas. <br />To fulfill the monitoring requirements of Rules 4.05.1 (2), 4.05.13(1)( c) and <br />4.24.4, it is necessary and appropriate to both understand and monitor water <br />levels and water quality at points above and below mining and along the <br />affected stream segment of the West Fork of Goodspring Creek and the <br />mainstem of Goodspring Creek. This method of hydrologic monitoring is long- <br />standing within the Division and the Coal Program and furthermore is <br />supported by past monitoring conducted at the Colowyo Mine (see alluvial well <br />A-6 and surface site EFGSC and alluvial well NGSW and surface site LGSC). <br />Therefore, the Division believes that an acceptable monitoring plan includes <br />monitoring the following alluvial wells on a quarterly frequency for field <br />pazameters (water level, EC, temperature, pH) and asemi-annual frequency <br />(2"d and 4~' quarter of calendaz yeaz) for lab samples (parameters as currently <br />approved). <br />- A-6 <br />- A-7 <br />- A-8 <br />- North Goodspring Well <br />- Gossazd Well <br />- MT-95-2 <br />This suggested plan reduces the number of water quality samples within one <br />year from the currently approved 16 samples to 12 while providing sufficient <br />data to determine impacts or lack of impacts to the shallow ground water <br />system in important alluvial valley floor azeas. <br />As mentioned, it is common practice to position alluvial wells with <br />corresponding surface sites to gather accurate and complete data in a specific <br />azea to understand the important and undeniable relationship between the <br />surface water and alluvial water system. This is supported by past and current <br />monitoring sites at the Colowyo mine. <br />Surface water sites are important because receiving stream standards, where <br />established on a stream system, apply in-stream and after mixing, with any <br />mine water discharge. While discharge monitoring of sediment ponds through <br />the Colorado Discharge Permit System relies on discharge samples and effluent <br />limitations, DRMS required water sampling programs provide data from <br />instream sample points above and below pond discharges where receiving <br />stream standards apply. While the Division concurs with Colowyo that CDPS <br />sampling of pond discharges can be a precursor or early indicator of a possible <br />